Only a dictator can save Oxford now. Local government simply cannot grasp how precious this marvellous, unrivalled city is, and how easy it will be to erode it into bare, dispiriting bleakness and ugliness. Any fool can see that the ancient colleges of the university must be preserved, but the setting in which they stand has no reliable defenders. It is true that a plan to put a bypass through the ancient pastures of Christ Church meadow was defeated in 1968. But that was after 27 years of wrangling, during which this hideous megalo-maniac scheme was actually described as ‘indispensable’.

In the half century during which I have lived in Oxford, with a few breaks, the nibbling of developers and expanders has continued without cease. Harold Macmillan famously allowed the destruction of the stately old Clarendon hotel in Cornmarket when he was housing minister in the early 1950s. It was replaced by a gigantic Woolworths, now defunct. The street, once picturesque, became ordinary and could now be in Wolverhampton. Colleges have squeezed funky 1960s blocks in among their ancient quadrangles. An enormous shopping mall, well-suited to Minneapolis, has arisen to the west of the centre, doing what such things usually do to the other shops in the city.

Meanwhile the old covered market, which in my teens was a flourishing, exciting place, slowly dies. Of the four main streets in the centre, the two beautiful ones are filled with incessant processions of shuddering buses. The two dull ones are subjected to a half-hearted pedestrianisation scheme. And there is much more of this sort of thing, the details too numerous to describe here. With very few exceptions, new university and college buildings are Bauhaus-style cuboids, which seem to get higher as the years go by.

But beyond that is a bureaucratic inability to understand the importance of scale, or of the green bowl of building-free landscape in which the city stands, or of the necessity of trees. Jan Morris, in her moving book on the city, describes the heart-stopping sight of its towers from the low hills to the west, as a brief patch of sunlight passes over the ancient stones. Go and see it while you can, is my advice.

Many have also loved the distant prospect across the ancient, never-ploughed space of Port Meadow, like a glimpse of the Celestial City. But in recent years that has been wrecked by a cluster of graduate housing, romantically called ‘Castle Mill’. It looks like a liberal prison, and the key thing is that hardly anybody seems to have realised just how ugly it would be until it was finished. There were then campaigns to have it demolished, or at least deprived of its top two storeys. But it was too late. There has instead been an attempt to camouflage it — which is a sort of admission of how hideous it is.

And now we have a new plan. This will destroy almost 100 mature trees in a conservation area, on a hillside to the east of the city. It will erect an estate of student barracks, some of them almost 60 feet high. The mass of it, on the slope, will be striking, to put it mildly. There are already student houses there, but they are low and small and hidden by woodland. If you have watched Inspector Morse when they have done one of those serene views of the city, you have probably seen the camera sweep across this spot, part of the green backdrop to the golden heart of Oxford. It is also visible from the high ground to the west where Jan Morris and Matthew Arnold alike once looked in wonder at one of the loveliest places on Earth.

This scheme is desired by Oxford’s other university, Brookes, which claims to need the extra space to house 500 students. It is desired by the local authorities, who bow down to a local plan which alleges that Oxford needs huge amounts of new housing. It was twice rejected by the city council. There were strong objections from those living nearby and also from the Oxford Preservation Trust, which warned of a ‘considerable intensification of development’ which ‘cannot be achieved without impacting on the Oxford views’. But just as the objectors were rejoicing at a rare victory over the development monster, the proposal somehow came back to life. It was approved last month by six votes to three at a meeting of a planning review committee which is said to be final. As the vote went through, a member of the public called out ‘Castle Mill!’, making a direct comparison with the previous planning disaster on Port Meadow.

Shall we wait to see if he is right? Shall we wait to see how it looks when the chainsaws get to work on the irreplaceable trees, when the stark massing of blocks rises amid the cranes and another little patch of beauty is sacrificed to the god of growth? Or is it time that we understood in this country that we have in Oxford a possession beyond price, which we inherited from our forebears and should leave undamaged to our heirs. It is not ours to destroy or damage.

Local government has had its chance to govern Oxford, and has made a dreadful mess of it. I think it is time for central government to put such places under the rule of a kind of Prefect, who does not need 27 years to know that a road across Christ Church meadow is a bad idea, and who understands that some things are more valuable than money. The joke used to be that Oxford, overpowered by car factories, would become ‘the Latin Quarter of Cowley’. The threat now is that it will become lost entirely amid crowds, noise and development, its spirit entirely vanished.